The Annapolis waterfront turned into a ghost town after flooding in 2012. Amy McGovern

Rising sea levels have kicked up flood days by as much as 900 percent along parts of the East Coast.

What's the most pernicious climate-change threat facing the U.S. in the years to come? It might not be lung-scorching air pollution, less-nutritious crops, or super-fueled wildfires, but rising sea levels repeatedly swamping coastal cities, according to a new NOAA report.

The number of "nuisance flooding" days in the U.S. has shot up markedly since the middle of last century, by as much as 925 percent in Annapolis and 922 percent in Baltimore. And as the oceans continue to swell—a byproduct of melting glaciers and the heat expansion of water—we can expect these waterlogged days to become yet more common, especially on the East Coast, says the report's lead author, William Sweet.

"Flooding now occurs with high tides in many locations due to climate-related sea level rise, land subsidence and the loss of natural barriers," Sweet says. "The effects of rising sea levels along most of the continental U.S. coastline are only going to become more noticeable and much more severe in the coming decades, probably more so than any other climate-change related factor."

Nuisance flooding occurs during high tides and often shuts down traffic, closes businesses, and hastens the deterioration of streets, railways, and auto underbellies with saltwater corrosion. These events are troublesome to communities when they're minor; when amplified by drenching downpours and wind-driven tidal surges, they can become ghastly fiascoes for waterfront communities. As one Annapolis resident told the media after a particularly nasty nuisance flood in December, 2012 (pictured above): "This was completely unexpected. This is higher than Sandy."

Flooding along the Potomac River in April 2011 in Washington, D.C. (Associated Press)

By looking at data from the 1960s onward, Sweet's team found that nuisance flooding is on the rise on all three U.S. coasts but is hitting certain places much harder. The Atlantic shore around the vicinity of Chesapeake Bay is enjoying frequent trips to the dunk tank because the land there is also sinking (partly due to groundwater pumping). That's why Norfolk is on NOAA's list of the nation's top-10 nuisance-flood areas; for various other reasons, so is Atlantic City, Philadelphia, and Washington, D.C. Down South there's been a 547 percent rise in flood days in Port Isabel, Texas. And waves lapping at smart-car tires is increasingly becoming the soundtrack for San Francisco, with a 364 percent bump in flood days.

Here is that top-10 list; for even more detail check out the full, quite-large report:

About the Author

Most Popular

  1. photo: A woman crosses an overpass above the 101 freeway in Los Angeles, California.
    Transportation

    Navigation Apps Changed the Politics of Traffic

    In an excerpt from the new book The Future of Transportation, CityLab’s Laura Bliss adds up the “price of anarchy” when it comes to traffic navigation apps.

  2. Three men wearing suits raise shovels full of dirt in front of an American flag.
    Equity

    How Cities and States Can Stop the Incentive Madness

    Economist Timothy Bartik explains why the public costs of tax incentives often outweigh the benefits, and describes a model business-incentive package.

  3. Design

    Reviving the Utopian Urban Dreams of Tony Garnier

    While little known outside of France, architect and city planner Tony Garnier (1869-1948) is as closely associated with Lyon as Antoni Gaudí is with Barcelona.

  4. photo: Swedish journalist Per Grankvist, AKA the "Scandinavian Malcolm Gladwell."
    Environment

    To Survive Climate Change, We’ll Need a Better Story

    Per Grankvist is “chief storyteller” for Sweden’s Viable Cities program. His job: communicate the realities of day-to-day living in a carbon-neutral world.

  5. People in the park at night in front of water
    Perspective

    Nairobi Should Rethink Its Colonialist Approach to Urban Design

    The road being built in Nairobi is for the rich. Even if it will no longer traverse the city’s major park, it’s not the future-thinking urban design that Kenya needs.

×